Do you mean that "The order of the elements that compare equivalent is the
order of insertion and does not change." (
https://en.cppreference.com/w/cpp/container/multiset") statement is wrong?
And a hint while being used with 'insert' method of 'std::multiset' is
considered as "A MUST", not as "A RECOMMENDATION"?


ср, 12 февр. 2025 г. в 11:35, Jonathan Wakely <cxx_at_[hidden]>:

>
>
> On Wed, 12 Feb 2025, 02:07 Александр Поваляев, <apovalyaev_at_[hidden]>
> wrote:
>
>> *[[[[My comments in bold]]]]*
>>
>> вт, 11 февр. 2025 г. в 22:04, Jonathan Wakely <cxx_at_[hidden]>:
>>
>>>
>>>
>>> On Tue, 11 Feb 2025 at 18:33, Александр Поваляев via Std-Proposals <
>>> std-proposals_at_[hidden]> wrote:
>>>
>>>> *[[[My comments in bold]]]*
>>>>
>>>> вт, 11 февр. 2025 г. в 21:06, Bo Persson via Std-Proposals <
>>>> std-proposals_at_[hidden]>:
>>>>
>>>>> On tis 2025-02-11 at 09:29, Александр Поваляев via Std-Proposals wrote:
>>>>> > A Proposal to Add a New Multiset container Method to the Standard
>>>>> > Library Technical Report
>>>>> >
>>>>>
>>>>> > C++ Containers library std::multiset
>>>>> >
>>>>> > (1) size_type reduce( const Key& key );
>>>>> >
>>>>> > (2)
>>>>> > template< class K >
>>>>> > size_type reduce( K&& x );
>>>>> >
>>>>> > (3) size_type reduce( const Key& key, size_type count );
>>>>> >
>>>>> > (4)
>>>>> > template< class K >
>>>>> > size_type reduce( K&& x, size_type count );
>>>>> >
>>>>> > This method acts in right the opposite way to how method 'insert'
>>>>> does.
>>>>> > Method 'reduce' decreases the number of std::multiset elements with
>>>>> > the same key value. And while being supplied within the second
>>>>> argument
>>>>> > 'size_type count', method 'reduce' decreases the number of
>>>>> std::multiset
>>>>> > elements with the same key value but several times.
>>>>> >
>>>>>
>>>>> How do we know if the function is to remove the oldest or the newest
>>>>> inserts? Or some in the middle?
>>>>>
>>>> *[[[Aleksandr]]] I believe it should be in the priority queue like
>>>> style. *
>>>>
>>>
>>> No, there is no priority here.
>>>
>>>
>>>> *https://en.cppreference.com/w/cpp/container/multiset
>>>> <https://en.cppreference.com/w/cpp/container/multiset> says "*
>>>>
>>>> *The order of the elements that compare equivalent is the order of
>>>> insertion and does not change.*
>>>> *(since C++11)**", so the oldest inserts should be deleted.*
>>>>
>>>
>>> It doesn't say anything about "oldest". You cannot know which are the
>>> "oldest", you can only know which are the closest to the beginning of the
>>> container.
>>>
>>> If you insert every equivalent element using a hint, you can put the
>>> newer elements before the older ones, or after them. So the order of
>>> equivalent elements is not in oldest to newest, or newest to oldest. It
>>> depends on how they were inserted.
>>>
>>
>> [[[[Aleksandr]]]] "The order of the elements that compare equivalent is
>> the order of insertion and does not change" (
>> https://en.cppreference.com/w/cpp/container/multiset) means that an
>> element which is inserted first will be the closest to the beginning of the
>> container amongst all the elements with the same key value.
>>
>
> That's not always true, because you can use a hint when inserting.
>
> s.insert(s.insert(1), 1);
>
> This inserts two equivalent elements and the newer one is closer to the
> beginning.
>
>
>
> And so, it will be the first element to be deleted by a 'reduce' method
>> call.
>>
> Let's call such an element as "oldest" amongst all the elements within the
>> same key value.
>>
>
>